Automatic pilot device



p 6 R. B. WALLACE ETAL AUTOMATIC PILOT DEVICE 3 Sheets-Sheet, 1

Filed July 25, 1962 Twmmy wo. mm R INVENTORS RICHARD B.WALLAOE BY P; OBERT J. EBBERT 3 run ATTORN YS p 1964 R. B. WALLACE ETAL 3,148,654

AUTOMATIC PILOT DEVICE Filed July 23, 1962 3 Sheets -Sheeo 2 INVENTORS RICHARD B.WALLAGE ROBERT J.EBBERT p 1964- R. B. WALLACE ETAL 3,148,654

AUTOMATIC PILOT DEVICE 3 Sheets-Sheet 3 Filed July 23, 1962 United States Patent 3,148,654 AUTOMATIC PHLOT DEVICE Richard B. Wallace, Bloomfield Hills, and Robert J.

Ebhert, Rochester, Mich, assignors to The Oakland Corporation, Birmingham, Mich, a corporation of Michigan Filed Juiy 23, 1962, Ser. No. 211,617 21 Claims. (Cl. 114-144) The present invention relates to an automatic pilot device, and more particularly to such a device using the pressure differential such as available at the engine of a boat or furnished by a separate pump to effect control of a fluid pressure motor.

It is an object of the present invention to provide an automatic pilot device having a'rudder separate from the usual existing rudder or rudders provided on the boat, and adapted to effect automatic steering while the usual rudders are left free or maintained. in neutral position.

It is a further object of the present invention to provide an automatic pilot device including a substantially balanced rudder including a trim or servo-tab rudder, also substantially balanced, adapted to position the separate rudder to the required steering position.

It is a further object of the present invention to provide an automatic pilot device having rudder means, a pair of fluid pressure motors, means for controlling the motors in accordance with the heading of the boat to effect automatic movement of the rudder means to the required position to maintain a desired heading.

More specifically, it is an object of the present invention to provide a constructionas defined in the preceding paragraph in which the fluid pressure motors comprise opposed bellows and particularly a pair of opposed be1-- lows havin a common intermediate wall and having the outer walls of the bellows mounted for movement respectively toward and'away from the common intermediate wall.

Still more specifically, it an object of the present invention to provide, in apparatus of the character described in the preceding paragraph, a pair of book type bellows having a common intermediate wall and outer walls mounted for swinging movement respectively toward and away from the common intermediate wall.

It is a further object of the present invention to provide an automatic pilot including vacuum motor mechanism for controlling the position or" a rudder and'a vacuum circuit including a bleed port, a compass card having closure" means associated therewith eifective to control said port, a pivot support for said compass card movable toward and away from said port to provide for movement of said compass card into a'position determined by the compass heading when spaced from said port and to provide for controlled closure of said port upon movement of said card toward said port;

It is a further object of the present invention to provide tem is sub-atmospheric and in which the port controlled.

position between said body and member when said member is brought into juxtaposition to said body.

More specifically, it is an object of the present invention to provide a condition responsive device comprising a body, a pivot support movable in a direction substantially perpendicular to the surface of said body, a member carried by said pivot support for rotation about its axis and for movement with said pivot support between a signaling position in engagement with said surface and a condition responsive position spaced from said surface, and signaling means carried by said body and said member. I

It is a further object of the present invention to provide a condition responsive devicev comprising a support body having a surface provided with a bleed port therein, a pivot support movable in a direction substantially perpendicular to said surface, a condition responsive valving element carried by said pivot support and including a valving portion adapted to control said port, said valving element being rotatable on said support in accordance with variations in the condition to be sensed when moved by said.

support out of engagement with said surface.

It is a further object of the present invention to provide a condition sensitive device as described in the preceding paragraph in which said condition responsive valving element is a compass element and preferably a magnetic compass card.

It is a further object of the present invention to provide to provide an automatic pilot comprisnig rudder means, fluid pressure actuated motor means connected to said rudder, a compass including a rotatable compass card,

means for establishing a pressure differential at said motor means including a fluid pressure distribution system, and

valve means controlling said fluid pressure distribution system including a port controlled by said compass.

It is a further objectof the present invention to provide an automatic pilot device as described in the'preceding paragraph in which the fluid pressure applied to the sysby said compass is an atmospheric bleed port.

position sensitive means comprising a pair of relatively movable members including means effective to develop a signal determined by the relative position of saidmembers when in juxtaposition, and means for effecting relative movement-between said members toward and away from each other, and means for supporting one of said members for movement relative to the other of said members when separated therefrom in accordance with varia- I It is a further object of the present invention tov provide an automatic pilot device as described in the preceding paragraph in which the compass includes a compass card, a pivot support for said compass card, and means for moving said pivot support axially to move said compass card away from said bleed port to permit rotation thereof under the influence of the magnetic field and for movement into cooperating position with said bleed port to effect control of the rudder. I

Other objects and features of the invention will become apparent as. the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

FIGURE 1 is a more or less diagrammatic plan view of a boat to, which the present automatic pilot device is applied.

FIGURE 2 is an enlarged fragmentary side elevational View of the automatic pilot rudder.

. FIGURE 3 is an elevational view partly in section, of the control mechanism for the rudder.

FIGURE 4 is an elevational view similar to FIGURE 3, looking to the right as seen in FIGURE 3. FIGURE 5 is a front elevational view of a fluid distribution and support plate used in the automatic pilot device.

FIGURE 8 is a top plan view of the plate shown in FIGURE 5.

FIGURE 9 is a bottom in FIGURE 5.

Patented Sept. 15, 1964 plan view of the plate shown FIGURE is a sectional view of the plate taken on the line 10-10, FIGURE 7.

FIGURE 11 is a fragmentary sectional view of the plate taken on the line 1111, FIGURE 5.

FIGURE 12 is an enlarged axial section of the adjustable bleed port mechanism employed in the system.

FIGURES 13 and 14 are diagrammatic views showing variations in the shape of bleed ports.

Referring first to FIGURE 1 there is illustrated more or less diagrammatically a boat 10 having a pair of rudders 12 and 14 which are connected to suitable manual operating devices such as a tiller (not shown). In accordance with the present invention an additional rudder 16 is provided which is associated with power means for adjusting it as required to maintain a preselected heading. The rudder 16 is mounted intermediate its ends on a post 18 for adjustment about a substantially vertical axis. It will be observed that the location of the post 18 is such that when the rudder is inclined to the direction of movement of the boat 10 the reaction forces between the rudder and water are largely balanced so that a very small force is required to turn or hold the automatic pilot rudder 16.

The rudder 16 carries a trim or servo-tab rudder 20 which is mounted for angular adjustment about a vertical axis by means of a pivot support shaft 22 and an upwardly extending shaft 24 which has rigidly connected thereto an actuating arm or lever 26. It will be noted that the vertical axis about which the trim rudder 20 is angularly adjustable is also located intermediate between its fore and aft edges so that little effort is required to adjust or retain the trim rudder 20 in adjusted position. The location of the axis of the post 18 and the pivot supports 22, 24 is such that while the boat is going forwardly small forces are developed tending to restore the rudder 16 or trim rudder 20 to intermediate position.

Mounted on the upper rear portion of the automatic pilot rudder 16 is a fluid pressure motor unit indicated generally at 28, which as best seen in FIGURE 1 comprises a pair of book-type bellows having inner side plates in abutment with each other or with a common support, and outer side plates 32 and 34 movable toward and away from the stationary inner side plates 30. Suitable pivot means (not shown) are provided for mounting the outer side plates 32 and 3-4 for substantially pivotal movement about vertical axes.

The side plates 30, 32 and 34 are of course connected by flexible bellows material indicated at 36. The side plates 32 and 34 carry operating arms 38 and 40 respectively, which in turn are connected by links 42 and 44 respectively to the arm or lever 26. 7

From the foregoing it will be apparent that when a fluid pressure differential is established so as to swing the side plates 32 and 34 in one direction or the other, the trim rudder 20 is moved to an angularly adjusted position which in turn will develop forces causing the automatic pilot l rudder 16 to move to a predetermined angular position. Thus, relatively small forces applied through the fluid motor unit 28 is effective to move the automatic pilot rudder 16 to the required position and to maintain it in such position.

In accordance with the present invention, the pressure differences required to operate the fluid pressure motor unit 28 are developed from vacuum or sub-atmospheric pressure available in the engine of the boat 10. Although the exact operation will be described in considerable detail subsequently, it may be pointed out at this time that the source of engine vacuum is connected to both of the bellows defined between the plates 30 and 32, and 30 and 34. In order to effect operation of the motor, bleed means are provided including atmospheric bleed ports which may be used to control the vacuum applied to the separate motors. In FIGURE 1 a passage 46 is connected to the source of engine vacuum, and through restrictions 48 and 50 and lines 52 and 54 to the separate vacuum motors. Line 52 is connected with a bleed passage 56 terminating in a bleed port 58, and line 54 is connected to a bleed passage 60 terminating in a bleed port 62. A compass card 64 is provided having an enlarged circumferentially extending edge valving portion 66. With the parts in the position illustrated in FIGURE 1 it will be apparent that the enlarged portion of the compass card covers the bleed ports equally so that equal vacuum will be available in the two motors. If however, the heading of the boat changes while the parts are adjusted to maintain the illustrated heading, the opening of one of the ports is increased and the opening of the other bleed port is correspondingly reduced, thus establishing different pressures in the two vacuum motors.

Referring now to FIGURES 3-12 there is illustrated the specific control means for the vacuum motors. Dcscribed in general terms, this comprises means for establishing a vacuum connection periodically to both of the vacuum motors, the degree of vacuum attained in each being controlled by a separate bleed port. The application of vacuum is controlled by valve structure oscillated back and forth by suitable motor means which conveniently may take the form of an ordinary windshield wiper motor.

Referring specifically to the figures, there is shown a support plate 70 details of which are best seen in FIG- URES 5-11. First however, it may be noted that the support plate 70 is mounted on a mounting plate 72 by screws '74. At its upper end the support plate 70 is connected to a housing 76 by a disc 78. The support plate 70 has a bracket 30 fixed thereto opposite ends of which are laterally offset as indicated at 32 and are connected to a conventional windshield wiper motor 84. The motor 84 includes a shaft 86 which extends through an opening 88 and has fixed thereto a valve disc 90 and a cam 92.

Means are provided for adjustably mounting a plate having a pair of bleed ports therein, and this means comprises a barrel 94 extending through an opening 96 provided in the plate 78, and a spool 98 rotatably mounted in the barrel 94. Details of this construction are best seen in FIGURE 12. The barrel 94 includes at its upper end a radially outwardly extending flange 100 adapted to rest upon the upper surface of the plate 78 so as to support the barrel and spool assembly. The barrel 94 includes a pair of passages 102 and 104 each communicating respectively through passages 106 and 108 with ports located at the inner surface 110 of the barrel. The spool 98 includes a radially outwardly extending flange 112 which rests upon the upper surface of the barrel 94 when the parts are assembled together, and the parts are retained in position by a lock ring 114 received in a groove at the lower end of the spool. The spool 98 includes an atmospheric bleed port 58 opening into its upper surface which communicates through a passage 118 with an armate port 120 which confronts the port 106a provided by the intersection between the passage 106 and the inner surface 110 of the barrel 94. Similarly, atmospheric bleed port 62 communicates by a passage 124 with an arcuate port 126 which confronts the port 103a provided by the intersection between the passage 108 and the inner surface 110 of the barrel 94.

360 degrees extent so that the spool 98 may be adjusted through a complete revolution.

The spool 98 has a vertically extending opening 130 extending completely therethrough which receives a vertically reciprocable pivot pin 132. The upper end of the pivot pin 132 is pointed and serves as a pivot mounting for the compass card 64. The compass card 64 may have the configuration best illustrated in FIGURE 1 so that in an intermediate position it equally, partially or completely closes the ports 53 and 62. As the compass card is turned relative to the spool 98 from the neutral position the ports 58 and 62 are differently restricted. For example, in the neutral position, the ports may be only partly closed so that upon relative movement between the compass card and spool, one of the ports is increasingly restricted while the other port is correspondingly restricted to a lesser degree. The compass card 64 as is usual in this type of device, is provided with a'bearing such for example as a jeweled bearing 134 so that the compass card is freely rotatable whenever the pivot pin 132 is raised to move the compass card out of contact with the upper fiat surface of the spool 98.

Means are provided for adjustingthe spool so as to control the heading at which the automatic pilot maintains the boat. This means comprises a gear 136 in mesh with the gear 128, the gear 136 being pinned or otherwise secured to an operating shaft 138 as indicated at 140. At its upper end the shaft 138 has secured thereto an adjusting knob 142, the knob being provided with a conical graduated skirt 144 having indicia thereon showing the heading to which the automatic pilot is adjusted. It will of course be apparent that when the spool 98 is angularly adjusted, the ports 53 and 62 therein are turned relative to the boat, and the automatic pilot mechanism will then cause the boat to turn to bring it to the required heading.

The motor 34 causes the cam to oscillate back and forth through a predetermined arc and this cam actuates a bell crank 145 one arm of which includes a follower 148 engageable with the periphery of the cam 92, the other arm including a bent-over flange 150 adapted to engage the underside of the pin 132. The bell crank 146 is pivoted as indicated at 152 to the support plate 70.

The valve disc 90, which is also aflixed to the shaft 86 of the motor 84, has its rear planar surface in abutment with the vertically extending front surface of the support plate 70; The valve disc 90 includes a pair of pockets 154 and 156 located 180 degrees apart, and a pair of recesses 15% and 160 also located 180 degrees apart. As will subsequently appear, the recesses 154 and 156 when moved into registration with the two pairs of three aligned ports illustrated in FIGURE 4, serve to interconnect these ports. When the recesses 158 and 160, which open laterally into the edge of the valve disc 90, are in registration with some of these ports, the ports are vented to atmosphere, all as will subsequently appear from the description of the circuitry. v

Referring now more specifically to FIGURES 5l1, the support plate '70 at its lower end is provided with tapped openings 162 for receiving the assembly screws 74 previously referred to. At its upper end the support plate 70 is provided with tappedopenings 164 to receive the screws by means of which the plate is connected to the disc 78. The front surface 166 of the plate 70 is provided with ports 168, 170, 172, 174, 176 and 178. It will be observed that the ports 170 and 176 are relatively small and constitute restrictions in the passages communicating with the ports. The support plate 71) is provided with an internal passage 180 extending upwardly from the lower end thereof which communicates with a channel 182 formed in the rear surface 134 of the plate 70. The channel 182 traverses the relatively small or restricted port 170 and includes an extension 186 leading to the small or relatively restricted port 176. It may be mentioned at this time that the channel 182 and the corresponding additional channels later to be described are closed by covering the rear channeled surface 184 of the support plate 70 with a suitable sealing material such for example as a thin brass plate or a plastic sheet or film, such for example as nylon.

The support plate 70 is provided adjacent its lower end with a second bored passage 188 which communicates with a groove 190 formed into the rear surface 184 of 6 the plate 70, the latter extending to the port 172. A third drilled passage 192 extends upwardly from the bottom edge of the plate 70 into communication with a channel 194 formed in the rear surface of the plate 70 which leads to the port 174. .The rear surface of the plate 70 is provided with a channel 196 which extends from the port 178 to a drilled passage 198, and a channel 200 extends from the port 168 to a drilled passage 202.

The upper end of the support plate '70 is recessed as indicated at 2134 and is provided with an aperture 2% to receive a rivet 298 which is thereby countersunk to avoid interference with the bell crank 146.

An engine generated source of vacuum is connected by a suitable vacuum conduit to the passage 180 and thence through the passage formed by the closed channel 182 to the restricted ports 1% an 176. Passages 188 and 192 are connected by suitable external vacuum lines to the vacuum motors formed between the plates 31) and 32, and 3t? and 34 respectively. Thus, a vacuum source is adapted to be connected to the motors whenever the ports 1'74 and 176 are connected together, and whenever the ports 171) and 172 are connected together. Means are provided however, for dissipating the etfectiveness of the vacuum and this means comprises the bleed ports 168 and 178 which are in communication with the passages 202 and 118 respectively. With the valve disc 90 in the position shown in FIGURE 4, it will be observed that the three ports including, the port 168, are closed as are the three ports including the port 178, because therear flat surface of the valve disc 90 is in contact with the flat ported front surface 161% of the plate '70. When however, the valve disc 9th is rotated slightly in a counterclockwise direction the port 16% is vented to atmosphere .while the two remaining ports 170 and 172 remain closed. Similarly, the port 1'18 is vented to atmosphere while the two associated ports 174 and 176 remain closed. This rotation of the valve disc 91 is accompanied by a corresponding rotation of the cam 92, swinging the bell crank .146

clockwise and raising the compass card out of contactwith the ports 58 and 62. At this time the compass card will of course be free to swing into alignment with the magnetic field so that it is responsive or sensitive to displacement between the boat and its preselected heading.

'When the cam 92 and valve disc 91) rotate in a clockwise 154 formed in the rear surface of the valve disc 9%). Sim

ilarly, the three ports including the port 178, become interconnected through the pocket 156 formed in the rear surface of the valve disc. At this time the cam disc is in the position which permits the compass card 64 to rest upon the'upper fiat surface of the spool 98 so that the atmospheric bleed ports 58 and 62 are restricted in accordance with the displacement between the compass card 64 and the spool 98.

As previously described, the ports 168 and 178 which are vented to atmosphere when in communication with the recesses 15% and 161i respectively, are atmospheric bleed ports and are in communication with the bleed ports 58 and 62 through vertical conduits 210 and 212. Conduit 21d interconnects passage zez to the passage 1M formed in the barrel $4. Conduit 212 connects passage 198 to the passage 1114 formed in the bottom of the barrel 94.

A separate vacuum supply line, indicated generally at 214, is provided which connects to the motor 84, and a suitable valve may be provided to control the speed of the motor.

With the foregoing description of connections it will be apparent that as the motor $4 is operated to oscillate the shaft 86 back and forth, connections are made periodically from the vacuum supply source connected to the passage 18%) and the passages 188 and 192 leading to the two opposed vacuum motors. While the valve' means is eifective to interconnect the ports 168, 170 and 172,

4' as well as to interconnect the ports 174, 176 and 178, the effectiveness of the vacuum applied to the corresponding vacuum motor is determined by the relative amount of closure of the atmospheric bleed ports 58 and 62. This in turn is controlled by the relative position of the compass card 64 and the aforesaid bleed ports.

The cam 92 is designed to provide for a predetermined interval of control of the bleed ports by the compass card 64- and a corresponding interval during which the compass card 64 is elevated and is free to turn into alignment with the magnetic field. Thus, the compass card 64 is freely movable to the required position by the extremely small forces available from the magnets built into the card as influenced by the magnetic field. At the same time the compass card is effective to provide a positive valving of the bleed ports so that the control of relatively large forces required to effect adjustment of the rudder is readily available.

So long as the boat heading differs from the selected heading, each interval during which vacuum is connected to the motors accomplishes an adjustment of the servo rudder in the direction required to correct the boat heading. The amount of such adjustment is of course dependent on the value of the restriction provided by ports 170 and 176. During the interval when the compass card is raised, ports 176, 172, 174 and 176 are closed and the steering motors held in their adjusted position. The system is thus effective to shift the trim rudder to a required position displaced from mid-position to maintain a heading and to hold it in such position without substantial movement.

Operation may be further controlled by shaping bleed ports 58 and 62 diiferently, for example, arcuately elongated, or of increasing radial dimension, as shown at 229 and 222 in FIGURES 13 and 14. Similar results can be obtained by shaping the valving edges of the compass card.

While the present invention has been illustrated in conjunction with an automatic pilot system, it will of course be apparent that certain features and aspects of the invention are capable of quite dissimilar uses. Thus for example, instead of employing a compass card movable toward and away from ports, in an adjacent support surface, it will be apparent that an element responsive to an entirely different condition might be substituted for the compass card. Thus for example, lateral forces might be developed between a pair of relatively movable bodies which vary in accordance with such conditions as speed; acceleration; deceleration; temperature; electrical variables such as current, voltage, strength of a magnetic field; or the like. Similarly, instead of developing a signal by empolying one of the movable elements or a portion thereof as valving means, the signal may be the result of the relative displacement between the members as a result of variable electrical conditions such for example as resistors.

In the foregoing description of the preferred embodiment of the present invention reference was made to a steering operation by applying a steering force to a servotab rudder mounted on and movable with a main steering rudder. This of course, especially when both the servotab rudder and the main steering rudder are so mounted as to largely balance the steering force, requires a minimum of power from the steering motor. Obviously of course, the invention is equally applicable to an arrangement in which the power means is connected directly to the steering rudder.

The foregoing description of the preferred embodiment of the invention makes use of a vacuum source available in the engine such for example as manifold vacuum. It is of course understood that the system may employ an entirely separate source of vacuum such for example as may be developed by a vacuum pump. Further, in its broader aspects, the invention is not of course limited to the use of vacuum as the source of a pressure differential,

but may employ pressure above atmospheric pressure as the source.

Finally, while the use of a single control system in which the bleed port or ports are alternately operative and inoperative has been disclosed herein and has proven very satisfactory in operation, it is within the contemplation of the present invention to provide two such units employing two independent separated compass cards. In this case the control units will be separated suificiently to prevent interaction between the magnets of the compass cards and the two separate units will be so timed that while one of the units is inoperative to exert a controlling effect on the power means, the other unit will be operative. The two control units will of course connect to a single power means. In practice, a single mo tor such as the vacuum operated motor 34, may be employed, having a shaft provided with two substantially separated valve discs such as and earns such as 92. Thus, whenever the boat is off course the power means will undergo continuous adjustment.

The drawings and the foregoing specification constitute a description of the improved automatic pilot device in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What we claim as our invention is:

1. In a system of the class described, a support, an element carried by said support for movement in a first direction between an operating position adjacent the support in which said element is retained against movement relative to said support in a second direction, and a second position in which said element is substantially freely movable in said second direction, and cooperating means on said support and element to develop a signal upon movement of said element to said first position dependent upon the position attained by'said element as a result of movement in said second direction while displaced from its sensing position, said cooperating means comprising a valve on said element and a valve port on said support.

2. The system defined in claim 1 in which said element is movable in said second direction to positions in which upon movement to sensing position it variably controls the opening of said port.

3. The system defined in claim 1 in which the cooperating means comprises a second port spaced from said first port, and in which said element is a valve operable selectively to equally and differentially control the opening of said ports in accordance with the position attained by movement thereof while displaced from said sensing position.

4. In a system of the class described, a support having a surfaceprovided with a port therein, a pivot post extending from said surface and movable axially relative thereto, a valve element pivotally mounted on said post and freely rotatable thereon when said post is moved away from said surface and engageable with said surface and cooperating with said port when said post is moved toward said surface, and fluid pressure responsive means connected to said port and actuated by fluid pressure controlled by said valve element and port.

5. In a system of the class described, a support having a surface provided with a pair of ports therein, a pivot post extending from said surface and movable axially relative thereto, a valve element pivotally mounted on said post and freely rotatable thereon when said post is moved away from said surface and engageable with said surface and cooperating with said ports when said post is moved toward said surface, and fluid pressure responsive means connected to said ports and actuated by fluid pressure controlled by said valve element and ports.

6. An automatic pilot system comprising a support plate having a port therein, a pivot post movable axially in a direction transverse to said plate, a compass card on said post freely rotatable thereon when said post is moved in a first direction to separate said card from said plate and engageable with said plate variably to restrict said port when said post is moved in the opposite direction.

7. An automatic pilot system comprising a support plate having a port therein, a pivot post movable axially in a direction transverse to said plate, a compass card on said post freely rotatable thereon when said post is moved in a first direction to separate said card from said plate and engageable with said plate variably to restrict said port when said post is moved in the opposite direction, a rudder, a fluid pressure motor connected to said rudder, and differential fluid pressure supply means controlled by said port and compass card and connected to said motor.

8. An automatic pilot system comprising a support plate having an atmospheric bleed port therein, a pivot post movable axially in a direction transverse to said plate, a compass card on said post freely rotatable thereon, when said post is moved in a first direction to separate said card from said plate and engageable with said plate variably to restrict said port when said post is moved in the opposite direction, a vacuum motor connected to said rudder, a vacuum source, a passage connecting said vacuum source to said motor, a passage connecting said bleed port to said motor, a timing valve controlling the connections between said vacuum source and said motor and bleed port, and means for moving said post axially back and forth and operating said timing valve in timed relation thereto.

9. An automatic pilot system comprising a support plate having a pair of atmospheric bleed ports therein, a pivot post movable axially in a direction transverse to said plate, a compass card on said post freely rotatable thereon when said post is moved in a first direction to separate said card from said plate and engageable with said plate variably to restrict said ports When said post is moved in the opposite direction, a rudder, a pair of expansible chambers having movable walls, means connecting said walls to said rudder, a vacuum source, passages connecting said source to said chambers, passage means connecting said ports to said chambers, a valve for cutting off said source, and means for operating said valve and oscillating said post in timed relation to open said valve only when said card is in engagement with said plate.

10. A system as defined in claim 9 in which said plate is angularly adjustable to determine the boat heading.

11. A system as defined in claim 9 in which said chambers are bellows having end Walls relatively pivotally movable, and in which said bellows are interconnected with end walls in back-to-back relationship.

12. An automatic pilot for a boat or the like comprising a fluid motor adapted to be connected to rudder means, a source of differential fluid pressure, a compass comprising a direction sensitive movable valve element, means including said valve element for controlling the application of fluid pressure from said source to said motor, means for alternately releasing said valve element for movement in accordance with variations in boat heading and moving said element into valving position in which said element is restrained from movement in accordance with variations in boat heading.

13. An automatic pilot for a boat or the like comprising a fluid motor adapted to be connected to rudder means, a source of differential fluid pressure, a support adapted to be fixed to the boat including a surface having a port therein, a compass card, means mounting said card for movement into and out of engagement with said surface and for free pivotal movement While out of engagement with said surface, said card having a valving portion thereon cooperable with said port to control the opening thereof, and means including said port and valving portion controlling the application of fluid pressure differential from said source to said motor.

14. An automatic pilot system comprising a vacuum motor, a source of vacuum, an atmospheric bleedport, three juxtaposed ports, a first passage connecting said vacuum source to one of said three ports, a second passage connecting said bleed port to another of said three ports, and a third passage connecting said motor to the remaining one of said three ports, a valve member having a pocket therein adapted to connect said three ports, a compass card having a portion adapted to variably restrict said bleed port, a pivot member mounting said card for turning movement, means for reciprocating said pivot member and actuating said valve member in timed relation to move said card into cooperating relation to said bleed port and to interconnect said three ports.

15. An automatic pilot system comprising a vacuum motor, a source of vacuum, an atmospheric bleed port, three juxtaposed ports, a first passage connecting said vacuum source to one of said three ports, a second passage connecting said bleed port to another of said three ports, and a third passage connecting said motor to the remaining one of said three ports, a valve member having a pocket therein adapted to connect said three ports and a recess adapted to connect said bleed port to atmosphere, a compass card having a portion adapted to variably restrict said bleed port, a pivot member mounting said card for turning movement, means for reciprocating said pivot member and actuating said valve member in timed relation to move said card into cooperating relation to said bleed port and to interconnect said three ports, and thereafter to move said card away from said bleed port to provide for rotation thereof and to close the ports in the passages connected to the vacuum source and motor and to vent the bleed port to atmosphere.

16. An automatic pilot system for a boat comprising fluid actuated steering motor means, a source of differential fluid pressure, passage means connecting said source to said motor means, and means controlling the operation of said motor in accordance with heading of the boat comprising valve means including a movable compass having a valve portion connected thereto.

17. An automatic pilot system for a boat comprising fluid actuated steering motor means, a vacuum source, passage means connecting said source to said motor means, and means controlling the operation of said motor in accordance with heading of the boat comprising valve means including a movable compass having a valve portion connected thereto.

18. An automatic pilot system for a boat comprising a pair of vacuum motors adapted to be connected to a steering rudder to effect movement thereof in opposite directions, a vacuum source, vacuum passage means connecting said source to said motors, and means controlling the application of vacuum to said motors, said last means comprising a movable magnetic compass and valve means including a valve portion connected to said compass.

19. An automatic pilot system for a boat comprising a pair of vacuum motors adapted to be connected to a steering rudder to effect movement thereof in opposite directions, a vacuum source, vacuum passage means connecting said source to said motors, and means controlling the application of vacuum to said motors, said last means comprising bleed passage means connected to said vacuum passage means, a movable magnetic compass and bleed valve means in said bleed passage means including a bleed valve portion connected to said compass.

20. An automatic pilot system for a boat comprising a pair of vacuum motors adapted to be connected to a steering rudder to effect movement thereof in opposite directions, a vacuum source, a pair of vacuum passages connecting said source to said motors, a bleed passage connected to each of said vacuum passages, each of said bleed passages having a bleed port and a movable magnetic compass having bleed valve portions cooperable with said bleed ports.

21. An automatic pilot system for a boat comprising a pair of vacuum motors adapted to be connected to a steering rudder to effect movement thereof in opposite directions, a vacuum source, a pair of vacuum passages connecting said source to said motors, a bleed passage connected to each of said vacuum passages, each of said bleed passages having a bleed port and a movable magnetic compass having bleed valve portions cooperable with said bleed ports, said bleed valve portions being arranged to partially and equally restrict said bleed ports when the boat is on a desired heading, and to increase the restriction of one port and reduce the restriction of the other port on deviation from such heading.

References (Iited in the file of this patent UNITED STATES PATENTS Conti June 21, 1921 Flettner Sept. 2, 1924 Moore Aug. 31, 1943 Crise Sept. 7, 1948 Smith Apr. 29, 1958 Brandstadter May 20, 1958 Baltus et a1. Aug. 2, 1960 Newcomb July 3, 1962 

1. IN A SYSTEM OF THE CLASS DESCRIBED, A SUPPORT, AN ELEMENT CARRIED BY SAID SUPPORT FOR MOVEMENT IN A FIRST DIRECTION BETWEEN AN OPERATING POSITION ADJACENT THE SUPPORT IN WHICH SAID ELEMENT IS RETAINED AGAINST MOVEMENT RELATIVE TO SAID SUPPORT IN A SECOND DIRECTION, AND A SECOND POSITION IN WHICH SAID ELEMENT IS SUBSTANTIALLY FREELY MOVABLE IN SAID SECOND DIRECTION, AND COOPERATING MEANS ON SAID SUPPORT AND ELEMENT TO DEVELOP A SIGNAL UPON MOVEMENT OF SAID ELEMENT TO SAID FIRST POSITION DEPENDENT UPON THE POSITION ATTAINED BY SAID ELEMENT AS A RESULT OF MOVEMENT IN SAID SECOND DIRECTION WHILE DISPLACED FROM 